Vertex Shader has a store_out lowering pass that converts gallium driver
locations in offsets inside the VPM.
One of the consequences is that these offsets are consecutives; that is,
if the VS stores VARYING_SLOT_VAR0.xyz and VARYING_SLOT_VAR1.xyzw, there
isn't a hole in the VPM offsets for the un-stored VARYING_SLOT_VAR0.w.
Thus we need to change how the VPM offset is computed in the Geometry
Shader when loading the inputs.
This bug is exposed by !9050.
v2 (Iago):
- Include explanatory comment.
- Use assert.
Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
Signed-off-by: Juan A. Suarez Romero <jasuarez@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10129>